[Music throughout] The Wide Field Instrument
is the heart of WFIRST. The basic design is the same as
telescopes around the world. Light enters through WFIRST's
2.4-meter aperture. and is reflected and focused by the curved
main mirror. Additional elements tighten the beam even more, and strip it
of stray light rays before it passes through the filter wheel.
This wheel has a variety of filters that allow different wavelengths of light to pass through.
It spins from one to another depending on what the researcher
is looking for. FInally, the focused and filtered light reaches the
focal plane, where it creates an image on the detectors. In WFIRST's case,
there are 18 detectors, allowing it to create 300-million-pixel
images of large patches of the sky.
This combination of image size and detail has never been possible on a space-based
telescope before, and will make WFIRST an indispensable tool
in the future.